* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

ul {
  list-style: none;
}

a {
  text-decoration: none;
}

input,
textarea,
button {
  outline: none;
}

textarea {
  resize: none;
}

.fl {
  float: left;
}

.fr {
  float: right;
}

.clearfix::after {
  content: '';
  display: block;
  clear: both;
}

i {
  font-style: normal;
}

b {
  font-weight: normal;
}

/* 1、定义此类名的元素都应该相对于定位元素进行定位，且刚好水平垂直居中 */
.center {
	position: absolute;
	top: 50%;
	left: 50%;
	transform:translate(-50%,-50%);

}